Man on Trial for Allegedly Slaying Driver Who Killed His Sons

The murder trial begins today for a Texas father charged with gunning down a suspected drunken driver who struck and killed his two sons.

David Barajas, 32, is accused of taking the law into his own hands, executing the driver who authorities say killed his sons, ages 12 and 11, in a December 2012 crash.

The accident happened near Alvin, about 30 miles southeast of Houston. Barajas' truck had run out of gas, and he and the boys were pushing the truck down a rural road when Jose Banda, who investigators say was intoxicated, slammed into their truck and killed David Jr. and Caleb.

Prosecutors say the enraged father ran home, grabbed a gun and shot the 20-year-old in the head.

Cindy Barajas, mourning the loss of her two sons, is worried that she could lose her husband, too.

"Half of my life is gone. There's no bringing that back," she said, speaking exclusively to ABC News.

Cindy Barajas said her husband is innocent.

"The fact that they're sitting there trying to say that he did something he didn't do ... He was sitting there trying to revive my sons," she said.

Barajas has pleaded not guilty and says he didn't shoot anybody. The case features many complexities. Police never found the gun. The defense says there were no witnesses to the shooting.

Barajas has lots of support in the community: There's even a Facebook page dedicated to freeing him.

"While there appears to be evidence beyond all doubt of motive, what's lacking is credible evidence to prove that he's the one who pulled the trigger," Mark Eiglarsh, a Miami-based criminal defense attorney and legal analyst with no connection to the case, said.

Banda's family also set up a Facebook page, demanding his killer go to prison. Banda's fate should have been handled by the legal system, they argue.

"Whoever did it is getting away with murdering my nephew. He deserves justice," said Janie Tellez, Banda's aunt.

If convicted of murder, Barajas faces up to life in prison. Cindy Barajas remains adamant in her husband's innocence.

"Trying to take my husband away from me after my kids are gone, accusing him of something he didn't do ... I just don't think it's right," she said.